LOL.... :shock: But you still dont know why your fan dies..iso9001 said:Its an engine not a computer chasis... There is ~ a foot of room behind the fan.
EDIT: What do you mean protection ? It has a FUSE... What kind of protection are you looking for? Some sort of Overvoltage-proof-submerible-analog-to-digital-driven-microprocessor-running-at-3Ghz-and-a-ups-constantly-monitoring-ameter-with-built-in-temperature-alitiude-ultra-protecto-circuit ? Go look at your car, chances are it has an electric fan with a relay and a fuse. Thats it.
The conditions of the fan are not out of the ordinary and I'm certain the fan can handle being run for a long period of time with no damage (they are warranteed for 3 years)
What I'm wondering is if the fan siezed up why didn't it blow a fuse... Why after two dead fans has the fuse not poped (I checked the fuse with another and that didn't blow either.
I'm not sure what will happen with a lower rated fuse... If it doesn't pop just as this current one isn't popping then I have no idea where the problem could be.... Connecting the battery terminals with a 30amp fuse in between (ie: a shorted fan) should pop a 50amp fuse with no problem... If I put a lower amp fuse in and it DOES pop... well, then I guess I must have a crappy connection somewhere (no ?)
Ideas ?
iso9001 said:I'm using a relay since I already have one for the fan. NPNs are cheap. And I have found mosfets a little too 'sensitive" for my tastes. (I had this system on a mosfet that would trigger whenever it wanted to unless I touched the fet with my finger... the problem was it was not biased to ground... like I said, too sensitive. I just couldn't see that thing lasting forever). This fan has a reputation for being the best in the wold and I have not found another that could possibly fit this application. Besides I think the problem is with somthing else in the car.
The tech suggested that although he doesn't know the system that maybe I have a poor connection somewhere and its just enough stress on the fan to burn it up but not enough to blow my 30amp fuse ?
Does that stick ?
iso9001 said:Maybe I have a bad solder connector that is just roughly a few ohms poor of perfect that is heating up the fan ? (But that gets me back to the fuse again :?: )
well, maybe that was the problem then, there shouldn't be any solder on the brushes! :lol:iso9001 said:Part of the deal was that I can not open the motor w/o kissing my fan replacment goodbye. I have no idea what it looked like inside but was on the phone w/ the tech when he cracked it open. He said it was completely trashed. That the solder on the brushes had completely melted away.
thats true..are ya sure that this tech KNOWS what he is talking about..well, maybe that was the problem then, there shouldn't be any solder on the brushes! :lol:iso9001 said:Part of the deal was that I can not open the motor w/o kissing my fan replacment goodbye. I have no idea what it looked like inside but was on the phone w/ the tech when he cracked it open. He said it was completely trashed. That the solder on the brushes had completely melted away.
zevon8 said:One thing that there is alot of misunderstanding about in regard to fuses, they are really meant to protect the wiring, not the device. The other thing is that they do not respond instantly to the rated current.
For example, a 30 Amp fuse will not open circuit instantly at 30 Amps, infact, it is designed to carry 30 Amps. From the Littlefuse catalog, ( one of the worlds largest fuse producers ) a 30 Amp, ATO style automotive fuse has a MINIMUM opening time of 100 hours with 110% of rated current flowing through it. This means it will take a minimum of 100 hours to open circuit with 33 Amps flowing through it. For the same 30 Amp fuse to open circuit in less than 1 second ( maximum 600 seconds ), it requires 40 Amps.
You will definitely have done damage in this amount of time if the fan has a nominal operating current of about 12 Amps.
Taking into account the fans inrush current, even at say 20 Amps, for a duration of maybe 0.5 seconds, you need something more in the order of a 15 Amp fuse.
I think that this fan suffered from insufficient cooling, and baked itself. Fan motors are notorious for having extreme temperature rise, since they generally in their own airstream, and can/should be self cooling. It is not uncommon to see a rating of 60*C over ambient on a fan motor. Try touching something that is 60*C. And then remember that this is 60*C over ambient, so add the temperature of the radiator air to that figure.
At these temps, its really easy to melt solder, burn windings, dry-up and seize bearings, etc.
I think the manufacturer is giving you the run-around. If it was installed as marketed, used under normal operating conditions, and failed that quickly, something is wrong with it. Bottom line.
mechie said:Is it possible that the controller is starting and stopping the fan a LOT - causing it to draw the start-up current, stop again, draw the start-up current, with no rest (cool-down) time ?iso9001 said:The fan is controlled by a pic. It reads in the coolant temp sensor and triggers a NPN transistor to connect the relay coil to ground. This is a proven working system. And since its on the control side of the relay, and the relay is only triggering when its supposed to.
I don't like the "too much current" idea - too much current must have been caused by :-
- too much voltage (Phasor's idea)
- too frequent starting causing overheating of the motor coils
- faulty manufacture (as you said - unlikely - but not totally impossibe, are they from the same batch?)
- stalling (fairly obvious - dead dog wedged through radiator ?!)
Could the fan be happier without the PIC controller (just wired to ignition switch - a bit crappy but it could (dis)prove an idea)?
i see what you are saying , but with a FET i would use a Digital to Analog Converter, with a NPN power transistor your idea would work, he could get three different Values of resistors ... this is all assuming that the NPN will turn on with 25 mA , or less, applied to the base.. i dont see why not..plot said:mechie said:Is it possible that the controller is starting and stopping the fan a LOT - causing it to draw the start-up current, stop again, draw the start-up current, with no rest (cool-down) time ?iso9001 said:The fan is controlled by a pic. It reads in the coolant temp sensor and triggers a NPN transistor to connect the relay coil to ground. This is a proven working system. And since its on the control side of the relay, and the relay is only triggering when its supposed to.
I don't like the "too much current" idea - too much current must have been caused by :-
- too much voltage (Phasor's idea)
- too frequent starting causing overheating of the motor coils
- faulty manufacture (as you said - unlikely - but not totally impossibe, are they from the same batch?)
- stalling (fairly obvious - dead dog wedged through radiator ?!)
Could the fan be happier without the PIC controller (just wired to ignition switch - a bit crappy but it could (dis)prove an idea)?
maybe stick in a power mosfet controlled by the pic, and somehow code the pic to put out a few different levels of current... in this manner the fan would never be off, just slowed down and sped up.
maybe hook the base of the fet to two or three pins of the PIC with a resistor on each pin, output 111 to get full speed, 100 to get slowed down mode.
good , i was hoping that you didnt have to buy a new one..iso9001 said:oh hell.
I still have not found out what is wrong with the fans, but I did speak to another tech who said "yea, thats kind of a bullsh¡t answer" so I'm trying a newer slightly larger fan. Same diameter and everything just a larger motor... After speaking with a lot of different people I'm starting to think that maybe I just got 2 bad fans. They DID come out of the same batch I believe
I'm starting to think that nothing I have is screwed up. YES for the last time the fan spins the right way. YES my pic turns it on and off at the right temps w/ a 10degree dead band.
Seriously, using a mosfet AND a D/A? This is a 15-20amp fan. You do NOT want to try and use resistors, they'll be huge and hot. If I wanted to slow it down a little, PWM is the way to go. I recently found out thats how the OEM does it.
Mosfets may be better then my NPN (which I'm pretty sure will last forever). But they are too damn sensitive for my liking.
No one at this company ever heard of two bad fans, hell most people never ever ever heard of one. But since I cant figure out whats wrong with it, I'll just toss a new (free) fan in and watch.
iso9001 said:Resolution !
I got my new fans in today and so far so good. No problems, tried to abuse it all day and its working fine.
Looks like maybe I just got a bum fans from a company that tells me they have never before seen a bad fan at all. Go figure I get the only two ever made wrong. :?
Thanks for your help everyone,
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